@matheusbsbs / matheus-bagliano / commits / 21a2d4ada5

transport-helper: avoid reading past end-of-string

We detect the "import-marks" capability by looking for that string, but _without_ a trailing space. Then we skip past it using strlen("import-marks "), with a space. So if a remote helper gives us exactly "import-marks", we will read past the end-of-string by one character. This is unlikely to be a problem in practice, because such input is malformed in the first place, and because there is a good chance that the string has an extra NUL terminator one character after the original (because it formerly had a newline in it that we parsed off). We can fix it by using skip_prefix with "import-marks ", with the space. The other form appears to be a typo from a515ebe (transport-helper: implement marks location as capability, 2011-07-16); "import-marks" has never existed without an argument, and it should match the "export-marks" definition above. Speaking of which, we can also use skip_prefix in a few other places while we are in the function. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Jun 18, 2014 at 15:47 UTC 21a2d4ada52132e6b0b67f8e28aa4bcda416f7f2
1 file changed +7 -7
transport-helper.c
+7 -7
@@ -153,7 +153,7 @@ static struct child_process *get_helper(struct transport *transport)
153 write_constant(helper->in, "capabilities\n");
154
155 while (1) {
156 - const char *capname;
156 + const char *capname, *arg;
157 int mandatory = 0;
158 if (recvline(data, &buf))
159 exit(128);
@@ -183,19 +183,19 @@ static struct child_process *get_helper(struct transport *transport)
183 data->export = 1;
184 else if (!strcmp(capname, "check-connectivity"))
185 data->check_connectivity = 1;
186 - else if (!data->refspecs && starts_with(capname, "refspec ")) {
186 + else if (!data->refspecs && skip_prefix(capname, "refspec ", &arg)) {
187 ALLOC_GROW(refspecs,
188 refspec_nr + 1,
189 refspec_alloc);
190 - refspecs[refspec_nr++] = xstrdup(capname + strlen("refspec "));
190 + refspecs[refspec_nr++] = xstrdup(arg);
191 } else if (!strcmp(capname, "connect")) {
192 data->connect = 1;
193 } else if (!strcmp(capname, "signed-tags")) {
194 data->signed_tags = 1;
195 - } else if (starts_with(capname, "export-marks ")) {
196 - data->export_marks = xstrdup(capname + strlen("export-marks "));
197 - } else if (starts_with(capname, "import-marks")) {
198 - data->import_marks = xstrdup(capname + strlen("import-marks "));
195 + } else if (skip_prefix(capname, "export-marks ", &arg)) {
196 + data->export_marks = xstrdup(arg);
197 + } else if (skip_prefix(capname, "import-marks ", &arg)) {
198 + data->import_marks = xstrdup(arg);
199 } else if (starts_with(capname, "no-private-update")) {
200 data->no_private_update = 1;
201 } else if (mandatory) {